1. Field of the Invention
This invention relates to the corrosion inhibition of iron or metal containing iron in contact with water-in-oil emulsions.
2. Description of the Prior Art
In technical processes where iron or metals containing iron come in contact with aqueous systems, the problem of corrosion is encountered. These problems are particularly serious when the aqueous system is based on salt water as is normally the case in numerous natural oil recovery and treatment processes.
From German published application No. 24 37 920 adducts of maleic anhydride to longer chained unsaturated fatty acids are known which are used as corrosion inhibitors for salt water-in-oil emulsions. In some cases, however, these substances are not sufficiently effective.
From German Application No. 11 49 843 amine salts of amide acids are known which are obtained by reaction of, for instance, maleic anhydride with alkyl amines containing 4 to 30 carbon atoms per alkyl group and subsequent neutralization with such amines and which act among other things as rust preventives even in the presence of sea water.
However, these substances are either not water soluble or if they are in the form of lower amine salts are very difficult to dissolve in water, which prevents their use in water-in-oil emulsions which are to be separated later since the substances will then be present only in the oil phase thus allowing the salt water to freely corrode the iron which is present in the lines and in the vessels used.
The purpose of this invention was to determine substances which are effective as corrosion inhibitors in those petroleum-containing liquids which come in contact with iron or metals containing iron in the recovery, processing, transport, and storage of petroleum. That is, they must be soluble and/or dispersible in the water as well as in the oil phase of said liquids in order to uniformly protect the corrosion prone metals. Another goal of this invention consisted of finding such corrosion inhibitors which can be uniformly distributed at least in a colloidially dispersed form even in concentrated salt solutions.